Oscillation generator and frequency multiplier



March 12, 1940. J. REINAR'rz I OSCILLATION GENERATOR AND FREQUENCYMULTIPLIER Filed April 23, 1937 @ggf/ff 605 Cy m M m SCREE/VGR/DPOTENTIAL HARM/V/C FREQUENCY TUN/N6 HARMON/C E. FREOUENCYOl/TPUT|NVENTOR JOHN L. ENRTZ E /l/WM/ ATTORNEY Patented Mar. 12, 1940 r v v ,li

UNITED STATES PATENT 'OFFICE OSCILLATION GENERATOR AND FREQUENCYMULTIPLIER.

.lohn L. Reinartz, Manchester, Conn., assigner to Radio Corporation ofAmerica, a corporation of Delaware Application April 23, 1937, SerialNo. 138,508 4 Claims. (Cl. Z50-36) This invention relates to oscillationgenerator anda frequency multiplier stage, each stage corn-Ky andfrequency multiplier circuit arrangements. prising an electron dischargetube,

Many circuit arrangements have been designed Fig. 2 sho-ws a modicationof the second or in the past with the object o-f producingoscilfrequency multiplier stage, and y 5 lations at multiple frequenciesof the funda- Fig. 3 shows still another modification in which 5` mentalfrequency generator, but among the dethe two stages of oscillationgeneration and frefects'and deficiencies of such arrange-ments it quencymultiplication are suitably coordinated has been found that either thesedevices pro with but lone electron discharge tube of the twin duceoutput energy of a very low Value or else triode type.

the arrangement has been found lacking stability. Referring to Fig. l, Ishow an electron dis- :l0

Furthermore, if it is attempted to multiply the charge tube I preferablyof the pentode type fundamental frequency so as to obtain one of the inwhich are a, cathode 2, a control grid 3, a higher harmonics, that is,above the third or screen grid 4, a suppressor grid 5, and an anodefourth harmonic, the difficulty of maintaining 6. The input lcircuit forthis tube includes a grid an exact ratio between the output and thefunleak resistor 1 and a radio frequency choke 3 15 damental frequencyof the generator is very in circuit between the control grid 3 andground. much increased. The cathode 2 is coupled to ground by means Itis among the objects of my invention to of a capacitor S which may, ifdesired, be made provide a circuit arrangement including afunadjustable. Furthermore, the capacitor 9 and damental frequencyoscillation generator and a the choke 8 in combination form a tankcircuit 20 frequency multiplier such that output energy of which may betuned to one-half of the fundaconsiderable amplitude may be obtainedeven mental frequency of the oscillations to be genwhen this outputenergy is multiplied to one of erated in the tube l. This fundamentalfrethe higher harmonics of the fundamental frequency is the frequency atwhich a piezo-electric quency. element I0 is adapted to vibrate. Theelement 25 As a result of my experiments it has been I is connected inshunt with the resistive and` proven that the tenth harmonic of thefrequency reactive elements l and 8 respectively. of a generator havinga piezo-electric crystal The tube I has its screen grid ll biased at acontrol may readily be obtained where only two suitable positivepotential with respect to the electron discharge tubes are employed. IncarcathodeY 2, this biasing being provided bymeans 30 rying out my,invention I was able to produce of a potentiometer II across thepositive and the aforesaid tenth harmonic with a circuit arnegativeterminals of a suitable direct current rangement which delivered as muchas 10 watts source, as indicated by the plus and minus signs. of thisharmonic frequency. This was done with- The anode I5 derives positivepotential from this out exceeding the normal plate dissipation. source,the connection to the anode being made 35 It may readily be seen thatthe circuit arrangethrough the primary coil' I2 which forms with mentwhich I am about to` describe has considthe capacitor I3 a tank circuittuned to the funerable utility in short Wave radio apparatus. If,damental frequency of the generator. A by-pass forqexample, apiezo-electric crystal were to be condenser I4 is preferably connectedbetween the 40 employed having a frequency rating of, say, 3.75 screengrid lead and ground. Another oy-pass 40 megacycles (which correspondsto a wave length condenser I5 forms a coupling ConnectOn beof 80meters), the tenth harmonic 0f this fretween the positive side of the'D.C. source and quency would be suitable as a carrier wave of ground- Thenegative Side 0f this SCWO@ is 0f 37.5 megacycles, or 8 meters. Thissame crystal Course groupdedis also likely to prove useful in a circuitin which The? Cuult *auth-gement tuus far decnbed 45 the sixteenthharmonic would be developed and cglsggrll ltsssclajllteenetr l'llavmlt 1c as eve op a 1g Whle the mltrequey Ini ths bena 5 frequency, theconstancy of` which is controlled meferwa've a 1 a W e a no a' requmcyby the piezo-electric device Iii. of 60 megacycles.

i The anode 5 of the Atube I is coupled by means 50 My invention Wlllnow be descrlbed 1n detail, of a Capacitor gg to the control grid n ofan refel'elle being made t0 the accompanying dlaW' electron dischargetube I8 in a secondvstage of ing in which I I the circuit arrangement.This second stage Figure 1 ShOWS a typical Circuit arrangement serves asa frequency multiplier. The input cirhaving a fundamental frequencygenerator stage cuit for the tube I8 includes a radio frequency mi`choke I9 in series with a grid leak resistor 20,

these two elements being connected between the grid I'I and the groundedcathode 2 I. The anode 22 is fed with current from the positive side ofthe direct current source through the secondary transformer winding 23.This secondary winding forms with the adjustable capacitor 2li a tankcircuit tuned to a desired harmonic frequency of the fundamentalfrequency generated in the tube I. The coupling between the primary I2and the secondary 23 is preferably made adjustable.

Output energy at the desired harmonic frequency is taken olf through ablocking condenser 25 whence it is carried to any suitable utilizationdevice, not shown.

In order to appreciate the novel features of my invention attentionshould` be directed to the coupling arrangement between the outputcircuits of the two tubes.` This coupling between the primary winding I2and the secondary winding 23 provides a mode of operation which has ananalogy in the swinging of two pendulums, one at a fundamental frequencyand the other at a frequency harmonically related thereto. Theadjustment is such that the slow pendulum gives an impulse to the fastpendulum as often as their respective oscillations are in phase. Poweroutput from the fast pendulum can be obtained at any harmonic rate. Itwill thus be seen that the second stage of my circuit arrangement isenabled to deliver` considerably more power than would otherwise be thecase merely by virtue of the boosting effect of the output energy fromthe fundamental. frequency generator impressed across the interccuplingtransformer. This desirable result is only obtained, however, when theproper phase relationship exists between the transformer coupling andthe coupling between the anode 6 of the first stage and the control gridIl of the second stage, that is, through the capacitor IS.

It has been observed that in the operation of this circuit thedisconnection of the piezo-electric device causes oscillations to ceaseboth in the fundamental frequency generator and in the frequencymultiplier stage.

Referring to Fig. 2, I show the substitution of a screen grid tube "itfor the triode tube I8 of Fig. l. It will be seen that this screen gridtube is connected to the portion of the circuit lying to the left of thedot and dash line a--a in the same manner as has been heretoforedescribed with respect to the tube I8. It only nee-d be mentioned here,therefore, that the screen grid electrode 2l is supplied with a suitablepositive potential with respect to the cathode 2l and that preferablythe screen grid should be provided with a lay-pass condenser 25constituting a radio frequency path to ground. In other respects theoperation of the circuit arrangement shown in Fig. 2 will be fullyappreciated from the foregoing description of Fig. l.

Referring to Fig. 3, I show a twin triode electron discharge tube 35having a common cathode 3l, a grid 32 and an anode 33 in one triodeportion, and a grid Sil, an anode 35 in the other triode portion.Considering the electrodes 35, 32, 33, it may be seen that these areconnected to input and output circuits respectively in the same manneras is shown in Fig. 1 with respect to the tube i, that is to say, thereis a grid leak resistor 'I connected between the grid 32 and the cathode3i. There is also a piezo-electric device I connected between the grid32 and ground. Furthermore, there is an adjustable capacitor 9 formingwith the choke 8 a tank circuit tuned to one half of the fundamentalfrequency of the oscillation generator and of the piezo-electric deviceI0, this tank circuit being connected between the cathode 3i and ground.The anode Bil is connected to a positive d-c potential source throughthe primary I2 which forms with the adjustable capacitor E3 a suitabletank circuit tuned to the fundamental frequency. Referring to theelectrodes 3I, 34, 35, it will be seen that these are connected to inputand output circuits of a second stage, that is, a frequency multiplierstage, in the same manner as is shown for the tube I8 in Fig. l. Thus.the grid leak resistor is and the choke 2li are provided in the inputcircuit. The anode 35 is supplied with d-c positive potential throughthe transformer secondary 23, which secondary forms with the capacitor24 a suitable tank circuit tuned to the desired harmonic frequency. Theby-pass condenser 25 permits harmonic frequency energy to be taken olfand lead to any suitable utilization device. The operation of thecircuit arrangement of Fig. 3 will now be clearly understood from whathas been said with respect to Fig. 1.

In connection with a specic embodiment of my invention as shown in Fig.l, and as has been found to be suitable for generating a fundamentalfrequency of 3.55 niegacycles and where the eighth harmonic thereof or28.4 megacycles was developed in the output circuit of the multiplierstage, the following values have been found to be suitable:

In the input circuit of the tube i the grid leak had a value of 5,000ohms. The choke in series therewith had a value of 1GO microhenrys. Thecapacitor had a value of 100 micromicrofarads.

In the input circuit for the multiplier stage the grid leak resistor hada value of 50,000 ohms. The radio frequency choke in series therewithwas of such value as to substantially prevent the leakage of highfrequency energy to ground. The power output from the frequencymutilplier stage was in the neighborhood of 1I) watts when this stagewas tuned to the eighth harmonic. The frequency thus delivered was 28.4megacycles.

It will be understood that the circuit arrangements as herein shown anddescribed are merely illustrative of numerous circuit arrangements of ageneral type coming within the scope of my invention.

I claim:

l. An oscillation generator and frequency multiplier comprising anelectron discharge tube circuit arrangement constituted by two stageseach having an input portion including a control grid, an. outputportion including an anode, and a cathode system common to both portionsinthe two stages, a source of direct current operating potentialssuitably connected to said input and output portions, a tuned resonantcircuit connected between the cathode system and the grounded negativeterminal of said source, a piezo-electric device lconnected between thecontrol grid of the rst stage and ground, a grid leak resistor connectedbetween each control grid and the cathode system, a reactance in serieswith that one of said resistors which is in the second stage, tworesonant circuits having adjustably intercoupled inductances and adjustble capacitors, one of said resonant circuits being in the outputportion of the first stage and the other in the output portion of thesecond stage, a capacitor coupling the anode of the rst stage to thecontrol grid of the second stage, means for so adjusting the tworesonant circuits of the input and output portions in the first stagethat oscillations are generated at a fundamental frequency under controlof said piezo-electric device, and means for so adjusting the resonantcircuit of the output portion in the second stage i that oscillationsare generated therein at a harmonic of said fundamental frequency.

2. A device according to claim 1 and further characterized in that thereis but one electron discharge tube of the twin triode type in saidcircuit arrangement.

3. A two-stage electron discharge tube circuit arrangement comprisingtuned input and output circuits for the first stage and a tuned outputcircuit for the second stage, the first stage constituting an,oscillation generator and the second stage a frequency multiplier, apiezo-electric device for controlling the fundamental frequency of theoscillations" generated, a tank circuit resonant to one half of saidfundamental frequency connected in series with said piezo-electricdevice in the input circuit of said first stage, a grid leak resistor inshunt with said series connection, ca-

pacitive coupling means between the output circuit of the first stageand the input circuit of the second stage, and inductive coupling meansbetween the output circuits of the two stages, said output circuitsbeing tuned to different harrnonically related frequencies.

4. A circuit arrangement having a single electron discharge tube thecathode of which in combination with a first grid and a first anodeconstitute oscillation generatorelectrodes and the same cathode incombination with a second grid and a second anode constitute frequencymultiplier electrodes, a tuned circuit and a piezo-electric deviceserially disposed in an input connection between the cathode and firstgrid, said tuned circuit being resonant to one half ther naturaloscillation frequency of said piezo-electric device, inductivelyintercoupled output circuits connected from the cathode to the twoanodes respectively, said output circuits being tuned to differentharmonically related frequencies one of which is substantially the sameas said frequency of the piezo-electric device, and capacitive couplingmeans connected between said rst anode and said second grid.

JOHN L. REINARTZ.

